Palace officials say Japanese Emperor Akihito's heart-bypass surgery has successfully ended.

According to The Associated Press, the Imperial Household Agency said Saturday, Feb 18, that the operation safely ended about six hours after Akihito entered the operation room at the University of Tokyo Hospital. A medical team from the hospital, joined by another team from Juntendo University Hospital, operated on the 78-year-old emperor.

The surgery was scheduled after tests last weekend showed that Akihito's heart condition had worsened compared to a year ago.

Akihito has had various health problems in recent years, including pneumonia and prostate cancer. He has cut back on public duties but still appears regularly at events.